finish add product api

kbazaar/src/main/java/com/kampus/kbazaar/cart/Cart.java

@@ -1,8 +1,12 @@
 package com.kampus.kbazaar.cart;
 
 import com.kampus.kbazaar.promotion.Promotion;
+import com.kampus.kbazaar.promotion.PromotionDiscount;
 import com.kampus.kbazaar.shopper.Shopper;
 import jakarta.persistence.*;
+import java.math.BigDecimal;
+import java.util.List;
+import java.util.Optional;
 import java.util.Set;
 import lombok.AllArgsConstructor;
 import lombok.Getter;
@@ -21,7 +25,7 @@ public class Cart {
     private Long id;
 
     @OneToMany(mappedBy = "cart", cascade = CascadeType.ALL)
-    private Set<CartProduct> products;
+    private List<CartProduct> cartProducts;
 
     @ManyToMany(cascade = {CascadeType.ALL})
     @JoinTable(
@@ -34,9 +38,73 @@ public class Cart {
     @JoinColumn(name = "shopper_id", referencedColumnName = "id")
     private Shopper shopper;
 
+    public BigDecimal getEntireCartDiscountAmount() {
+        BigDecimal totalCost = this.getTotalCost();
+        Integer allProductQuantity = this.getAllProductQuantity();
+        return this.getPromotions().stream()
+                .filter(prom -> prom.getApplicableTo().equals("ENTIRE_CART"))
+                .reduce(
+                        BigDecimal.ZERO,
+                        (acc, prom) ->
+                                acc.add(
+                                        PromotionDiscount.getDiscountAmountFromPromotion(
+                                                totalCost, allProductQuantity, prom)),
+                        BigDecimal::add);
+    }
+
+    public Integer getAllProductQuantity() {
+        return this.getCartProducts().size();
+    }
+
+    public BigDecimal getTotalCost() {
+        return this.getCartProducts().stream()
+                .map(CartProduct::getFinalPrice)
+                .reduce(BigDecimal.ZERO, BigDecimal::add);
+    }
+
+    public BigDecimal getFinalTotalCost() {
+        return this.getTotalCost().subtract(this.getEntireCartDiscountAmount());
+    }
+
     public Cart addPromotion(Promotion promotion) {
         this.promotions.add(promotion);
         promotion.getCarts().add(this);
         return this;
     }
+
+    public Optional<CartProduct> addPromotionToProduct(Promotion promotion, String targetSku) {
+        Optional<CartProduct> cartProduct =
+                this.getCartProducts().stream()
+                        .filter(filtered -> filtered.getProduct().getSku().equals(targetSku))
+                        .findFirst();
+
+        cartProduct.ifPresent(cp -> cp.setPromotion(promotion));
+        return cartProduct;
+    }
+
+    public Cart addProduct(CartProduct cartProduct) {
+        Optional<CartProduct> existingCartProduct =
+                this.cartProducts.stream()
+                        .filter(
+                                filtered ->
+                                        filtered.getProduct()
+                                                .getId()
+                                                .equals(cartProduct.getProduct().getId()))
+                        .findFirst();
+
+        if (existingCartProduct.isPresent()) {
+            CartProduct existingCartProductFirst = existingCartProduct.get();
+            existingCartProductFirst.setQuantity(
+                    existingCartProductFirst.getQuantity() + cartProduct.getQuantity());
+            return this;
+        }
+
+        cartProduct.setCart(this);
+        this.cartProducts.add(cartProduct);
+        return this;
+    }
+
+    public CartResponse toCartResponse() {
+        return CartResponse.fromCart(this);
+    }
 }

kbazaar/src/main/java/com/kampus/kbazaar/cart/CartController.java

@@ -1,6 +1,5 @@
 package com.kampus.kbazaar.cart;
 
-import com.kampus.kbazaar.shopper.ShopperService;
 import lombok.RequiredArgsConstructor;
 import org.springframework.http.ResponseEntity;
 import org.springframework.web.bind.annotation.*;
@@ -10,30 +9,23 @@
 @RequiredArgsConstructor
 public class CartController {
 
-    private final ShopperService shopperService;
+    private final CartService cartService;
 
     @GetMapping("/carts")
     public ResponseEntity getCart() { // NOSONAR
         return ResponseEntity.ok().build();
     }
 
-    @PostMapping("/carts/{username}/products")
-    public ResponseEntity<String> addProduct(
+    @PostMapping("/carts/{username}/items")
+    public CartResponse addProduct(
             @PathVariable("username") String username,
             @RequestBody AddProductRequest addProductRequest) {
 
-        //          Cart cart = cartService.findCartByUsername(username);
-        //        Product product =
-        // productService.getProductBySku(addProductRequest.getProductSku());
-        //        if (product.getQuantity() < addProductRequest.getQuantity()) {
-        //            return ResponseEntity.badRequest().build();
-        //        }
-
-        //        return ResponseEntity.ok(cartService
-        //                .findCartByUsername(username));
-        //                        .addProduct(product)
-        //                .toAddProductResponse());
-
-        return ResponseEntity.ok("hey");
+        return cartService
+                .addProductByUsernameAndProductSku(
+                        username,
+                        addProductRequest.getProductSku(),
+                        addProductRequest.getQuantity())
+                .toCartResponse();
     }
 }

kbazaar/src/main/java/com/kampus/kbazaar/cart/CartProduct.java

@@ -1,27 +1,60 @@
 package com.kampus.kbazaar.cart;
 
+import com.kampus.kbazaar.product.Product;
+import com.kampus.kbazaar.promotion.Promotion;
+import com.kampus.kbazaar.promotion.PromotionDiscount;
 import jakarta.persistence.*;
+import java.math.BigDecimal;
+import java.util.Optional;
 import lombok.AllArgsConstructor;
+import lombok.Builder;
 import lombok.Data;
 import lombok.NoArgsConstructor;
 
 @Entity
 @Data
 @AllArgsConstructor
 @NoArgsConstructor
+@Builder
 public class CartProduct {
     @Id
     @GeneratedValue(strategy = GenerationType.IDENTITY)
     @Column(name = "id")
     private Long id;
 
-    @Column(name = "product_id")
-    private Long productId;
+    @ManyToOne
+    @JoinColumn(name = "product_id")
+    private Product product;
 
-    @Column(name = "quantity")
-    private Integer quantity;
+    @ManyToOne
+    @JoinColumn(name = "promotion_id")
+    private Promotion promotion;
 
     @ManyToOne
     @JoinColumn(name = "cart_id")
     private Cart cart;
+
+    @Column(name = "quantity")
+    private Integer quantity;
+
+    public BigDecimal getDiscountAmount() {
+        return PromotionDiscount.getDiscountAmountFromPromotion(
+                product.getPrice(), quantity, promotion);
+    }
+
+    public BigDecimal getPrice() {
+        return product.getPrice().multiply(BigDecimal.valueOf(quantity));
+    }
+
+    public BigDecimal getFinalPrice() {
+        return this.getPrice().subtract(this.getDiscountAmount());
+    }
+
+    public static Optional<CartProduct> of(Product product, Integer quantity, Cart cart) {
+        if (product.getQuantity() < quantity) {
+            return Optional.empty();
+        }
+        return Optional.of(
+                CartProduct.builder().product(product).quantity(quantity).cart(cart).build());
+    }
 }

kbazaar/src/main/java/com/kampus/kbazaar/cart/CartRepository.java

@@ -1,7 +1,10 @@
 package com.kampus.kbazaar.cart;
 
+import com.kampus.kbazaar.shopper.Shopper;
 import org.springframework.data.jpa.repository.JpaRepository;
 import org.springframework.stereotype.Repository;
 
 @Repository
-public interface CartRepository extends JpaRepository<Cart, Long> {}
+public interface CartRepository extends JpaRepository<Cart, Long> {
+    Cart findByShopper(Shopper shopper);
+}

kbazaar/src/main/java/com/kampus/kbazaar/cart/CartResponse.java

@@ -0,0 +1,56 @@
+package com.kampus.kbazaar.cart;
+
+import com.kampus.kbazaar.promotion.Promotion;
+import java.math.BigDecimal;
+import java.util.List;
+import java.util.Optional;
+import lombok.AllArgsConstructor;
+import lombok.Builder;
+import lombok.Data;
+import lombok.NoArgsConstructor;
+
+@AllArgsConstructor
+@NoArgsConstructor
+@Builder
+@Data
+public class CartResponse {
+    private Long cartId;
+    private List<Item> items;
+    private List<String> promotionCodes;
+    private BigDecimal totalCost;
+    private BigDecimal entireCartPromotionDiscount;
+    private BigDecimal finalTotalCost;
+
+    public static CartResponse fromCart(Cart cart) {
+        List<Item> items = cart.getCartProducts().stream().map(CartResponse::initItem).toList();
+
+        return CartResponse.builder()
+                .cartId(cart.getId())
+                .items(items)
+                .promotionCodes(cart.getPromotions().stream().map(Promotion::getCode).toList())
+                .totalCost(cart.getTotalCost())
+                .entireCartPromotionDiscount(cart.getEntireCartDiscountAmount())
+                .finalTotalCost(cart.getFinalTotalCost())
+                .build();
+    }
+
+    private static Item initItem(CartProduct cartProduct) {
+        return new Item(
+                cartProduct.getId(),
+                cartProduct.getProduct().getName(),
+                cartProduct.getQuantity(),
+                cartProduct.getPrice(),
+                cartProduct.getDiscountAmount(),
+                cartProduct.getFinalPrice(),
+                Optional.ofNullable(cartProduct.getPromotion()).map(Promotion::getCode).orElse(""));
+    }
+}
+
+record Item(
+        Long id,
+        String name,
+        Integer quantity,
+        BigDecimal price,
+        BigDecimal discount,
+        BigDecimal finalPrice,
+        String promotionCode) {}

kbazaar/src/main/java/com/kampus/kbazaar/cart/CartService.java

@@ -1,14 +1,39 @@
 package com.kampus.kbazaar.cart;
 
+import com.kampus.kbazaar.exceptions.InternalServerException;
+import com.kampus.kbazaar.exceptions.NotFoundException;
+import com.kampus.kbazaar.product.Product;
+import com.kampus.kbazaar.product.ProductService;
+import com.kampus.kbazaar.shopper.ShopperService;
+import java.util.Optional;
 import lombok.RequiredArgsConstructor;
 import org.springframework.stereotype.Service;
 
 @Service
 @RequiredArgsConstructor
 public class CartService {
+    private final ShopperService shopperService;
+    private final ProductService productService;
     private final CartRepository cartRepository;
 
     public Cart findCartByUsername(String username) {
-        return null;
+        return Optional.of(username)
+                .map(shopperService::getShopperByUsername)
+                .map(cartRepository::findByShopper)
+                .orElseThrow(() -> new NotFoundException("Failed to find cart by username"));
+    }
+
+    public Cart addProductByUsernameAndProductSku(
+            String username, String productSku, Integer quantity) {
+        Product product = productService.getProductBySku(productSku);
+        Cart cart = findCartByUsername(username);
+        // TODO: add deduct product stock logic here
+        return CartProduct.of(product, quantity, cart)
+                .map(cart::addProduct)
+                .map(cartRepository::save)
+                .orElseThrow(
+                        () ->
+                                new InternalServerException(
+                                        "Product out of stock or failed to add product to cart"));
     }
 }

kbazaar/src/main/java/com/kampus/kbazaar/promotion/PromotionDiscount.java

@@ -0,0 +1,36 @@
+package com.kampus.kbazaar.promotion;
+
+import java.math.BigDecimal;
+import java.math.RoundingMode;
+
+public class PromotionDiscount {
+    public static BigDecimal getDiscountAmountFromPromotion(
+            BigDecimal price, Integer quantity, Promotion promotion) {
+        if (promotion == null) {
+            return BigDecimal.ZERO;
+        }
+        return switch (promotion.getDiscountType()) {
+            case "FIXED_AMOUNT" -> promotion.getDiscountAmount();
+            case "PERCENTAGE" -> price.subtract(
+                    price.multiply(promotion.getDiscountAmount())
+                            .divide(BigDecimal.valueOf(100), 2, RoundingMode.HALF_UP));
+            case "buy1_get1" -> {
+                if (quantity >= 2) {
+                    yield price;
+                }
+                yield BigDecimal.ZERO;
+            }
+            case "buy2_get1" -> {
+                if (quantity >= 3) {
+                    yield price;
+                }
+                yield BigDecimal.ZERO;
+            }
+            default -> BigDecimal.ZERO;
+        };
+    }
+
+    public static BigDecimal divideDiscount(BigDecimal price, Integer divider) {
+        return price.divide(BigDecimal.valueOf(divider), 2, RoundingMode.HALF_UP);
+    }
+}

kbazaar/src/main/java/com/kampus/kbazaar/shopper/ShopperService.java

@@ -30,4 +30,10 @@ public ShopperResponse getByUsername(String username) {
                 .map(Shopper::toResponse)
                 .orElseThrow(() -> new NotFoundException("Shopper not found"));
     }
+
+    public Shopper getShopperByUsername(String username) {
+        return shopperRepository
+                .findByUsername(username)
+                .orElseThrow(() -> new NotFoundException("Shopper not found"));
+    }
 }